The present invention relates to a method and a device for safeguarding against manipulation of an odometer or a vehicle recorder in a motor vehicle.
With the vehicle control concepts in use today, it is possible to establish a connection between a vehicle cockpit and an engine control unit over a CAN interface. It is known that the mileage of an odometer provided in an vehicle can be entered into the engine control unit in the event of a fault and stored there. A fault diagnosis may be facilitated with this measure.
Unexamined German Patent 29 11 160 describes a device for preventing unauthorized startup of a vehicle having an information carrier connected preferably to the key provided for the mechanical locks of the vehicle and having an analyzer circuit which triggers a signal when the correct information has been entered. That reference describes in particular how the reading on an odometer and/or an elapsed time meter can be transferred to the vehicle key and stored there. Then the vehicle can be started up again only when the start of the odometer or the elapsed time meter is transferred back from the key into an analyzer unit on the vehicle during the startup operation. That publication is concerned with safeguarding against theft of vehicles but not with the manipulation of odometer readings or trip recorders, which has been occurring more and more frequently in recent times.
An object of the present invention is a simple and inexpensive method of safeguarding against manipulation of odometers or trip recorders in motor vehicles.
The present invention makes available a method of safeguarding against manipulation of odometers or trip recorders in motor vehicles in a simple and inexpensive manner. To perform such a manipulation effectively, changes in the instantaneous or stored mileage readings would have to be made both in the cockpit (i.e., the trip recorder) and in the control unit, and this is a much more complex and technically difficult job in comparison with traditional methods of manipulation.
According to a preferred embodiment of the method according to the present invention, an engine function of the motor vehicle is suppressed if the respective instantaneous and stored odometer readings do not match. As an additional effect, this measure makes available an effective deterrence or safeguard against theft of the vehicle.
If the respective odometer readings do not match, an alarm signal is advantageably triggered. Such an alarm signal may be either acoustic or optical or it may be relayed to a central security office by way of appropriate wireless connections. In conjunction with known positioning devices, a motor vehicle on which the odometer has been manipulated in this way can be located easily.
In a preferred embodiment of the device according to the present invention, when restarting the engine, the arrangement for determining the instantaneous odometer reading and/or comparing the odometer reading with a stored odometer reading is implemented in the form of a combination instrument, and the arrangement for prompting suitable measures for the case when the odometer reading found on restarting the engine and the stored odometer reading do not match is implemented in the form of a transmission control unit or an engine control unit. Such devices which are traditionally provided with motor vehicles can be modified in the sense of the function described here with little or no effort.